gas spewing out the cap??

VegasAnthony · Oct 3, 2005

94 XJ
About 3 weeks ago I started smelling fuel in(around) my cherokee
and today after filling up I parked and heard the pressure releasing though the cap ..so I start to loosent the cap and gas starts almost SHOOTING out!
I have no idea if the cap is supposed to be vented..

so basically the question is
how is the gas tank vented?
my Hanes Book shows 2 vent lines on the top of the tank..??
doesnt say anything about the cap itself

the engine runs fine..

Matthew Currie · Oct 3, 2005

It should vent through the top lines, unless the evaporative canister is clogged. But if you overfilled the tank so that the gas expanded into the filler, the level will be above the vents and you may get a face full because the vent lines are very small, and the canister is ineffective if it is soaked.

Under normal circumstances the cap doesn't vent at all (for environmental reasons), but it has vacuum and pressure relief valves in it to prevent the tank from collapsing when fuel is drawn out, or exploding when it expands.

My guess is that you filled the tank too full. Remember that gasoline expands a great deal when it warms up, and usually is pumped from a cool underground tank. But it might be wise to check the vent lines and the canister too to ensure that they're not clogged.

RichP · Oct 3, 2005

Also keep in mind that those caps do go bad, bad enough that they will trigger a check engine light.

VegasAnthony · Oct 3, 2005

Matthew Currie said:
It should vent through the top lines, unless the evaporative canister is clogged. But if you overfilled the tank so that the gas expanded into the filler, the level will be above the vents and you may get a face full because the vent lines are very small, and the canister is ineffective if it is soaked.

Under normal circumstances the cap doesn't vent at all (for environmental reasons), but it has vacuum and pressure relief valves in it to prevent the tank from collapsing when fuel is drawn out, or exploding when it expands.

My guess is that you filled the tank too full. Remember that gasoline expands a great deal when it warms up, and usually is pumped from a cool underground tank. But it might be wise to check the vent lines and the canister too to ensure that they're not clogged.

I only had 3/4 of a tank when ithis happened

I believe Mattew called it right
ijust checked the Haynes book and it states

"The most common symptom of a fault in the evaoparative emissions system is a strong fuel odor in the engine compartment"

thanx

Anthony

gas spewing out the cap??

VegasAnthony

NAXJA Forum User

Matthew Currie

NAXJA Member #760

RichP

NAXJA Forum User

VegasAnthony

NAXJA Forum User

Similar threads